A crank-CVT transmission is known, for example, from DE 102 43 533 A1. This transmission has a driving shaft, for example a transmission input shaft, which can be coupled to an engine, and at least one driven shaft, for example a transmission output shaft, which shafts can have a drive connection to one another. Furthermore, this transmission has a freewheel device. In this context, the freewheel device is composed of a plurality of freewheel units which are arranged axially one behind the other around the driven shaft and which can be shifted. This means that the blocking direction of the clamping bodies with respect to the two rings which can be rotated with respect to one another can be shifted. By using such freewheel units it is easily possible to change the direction of rotation of the shaft in the transmission and therefore implement, for example, a reverse gear speed. Additional direction shifting transmissions, for example planetary gear mechanisms, are not necessary.
In order to shift the blocking function of the freewheel, in DE 102 43 533 A1 a shifting device is provided which has a plurality of shifting units which are each arranged between adjacent clamping bodies. The shifting units can be activated synchronously and have shifting means which each have a rotatable, disk-shaped region and a profiled region, which is preferably composed of a profiled rod. A spring, which is formed by a leg spring, is provided on the profiled region. The spring can be clamped between the profiled region and a clamping body. The profiled rods and the means of activating the shifting can extend axially through all the freewheel units, with the result that when the profiled rods are rotated all the freewheel devices can be shifted at the same time in order to be able to shift the freewheels of a crank-CVT transmission so as to change the direction of travel of a vehicle, the crank-CVT transmission must be load-free. For this reason, the output unit of the crank-CVT transmission must be decoupled from the differential. In previously known crank-CVT transmissions, decoupling or unlocking of the output unit and the activation of the shifting are carried out by means of multi-disk clutches or by means of a plurality of shifting sleeves. In this context, the multi-disk clutches or the shifting sleeves have the function of actuators.
The unlocking or decoupling of the output unit by means of multi-disk clutches or shifting sleeves has the disadvantage that a multiplicity of actuators is often also necessary for a multiplicity of freewheels. A multiplicity of actuators requires a relatively large amount of installation space for the crank-CVT transmission. This means that as the number of actuators increases there is an accompanying increase in the space required in the crank-CVT transmission. In addition, the decoupling process has to be matched chronologically to the shifting process by a suitable controller.
On this basis, the object of the invention is to provide a crank-CVT transmission which has a single actuator for decoupling the drive unit and for initiating the shifting of the freewheel.